I Obtained a Mythic Item - Chapter 361

Going for a swim, she ends up in an ancient wild Beast World and ends up being brought home by a handsome wolf.
She wants to stick to the handsome wolf, stock some salt, farm some land, look at some handsome men and grow old like that, but the handsome wolf pounces on her every day.
What? He wants her to have babies?
NO~ NO~ NO~ There is no happy ending to interspecies marriages, hurry and let go of me handsome wolf~

- Description from Novelupdates

【Hilarious and Adorable Novel】As a military doctor with expertise in both Chinese and Western medicine, Gu Changsheng felt that this time-traveling journey was ridiculously screwy!Once he traveled back, he was gifted a son, hmm, it felt quite nice.Having a son to rely on in old age, plus owning a steady estate, wealth and glory weren't hard to come by.A lousy father turns over a new leaf? Sorry, mom here isn't fond of revisiting the past!Son, what kind of dad do you want? From the multitude of handsome and wealthy young men out there, let’s pick and choose…This is the story of a bizarrely outstanding female doctor, strutting through ancient times with her child in tow!

He rose from abjection and achieved eternity in glory.
He embraced the prettiest beauties and killed the strongest opponents.
He was able to shift the clouds into rain and cover the sky with one hand.
He could overrun the entire world and go anywhere as he pleased.
He pacified wars and held the world in awe.
He was matchless in the world.
However, his hair turned white overnight for his beloved woman and he was on the verge of death.
He was surrounded by enemies who were trying to take his life.
He struggled his way to become mighty and fought for everything he cherished.
For this age, he was the only king of the Dark World.
His name was a byword for might.
As a man living in the world, his only ideal was to pursue brilliance.

- Description from Novelupdates

The world was once at war with 10 alternate worlds. This was known as the Concept War and our world won 60 years ago. All of this was concealed so no normal people are aware of this fact in the current time.

After the death of his grandfather, the high-school student Sayama Mikoto is suddenly summoned by the giant corporation IAI. He learns this world is headed for destruction due to the acceleration of the Minus Concepts. To prevent this, negotiations must be undertaken with the survivors of the other parallel worlds so their 10 concepts can be released.

And so Sayama is caught up in the final battle to clean up after the Concept War which left behind so much enmity.